Doctor Who has been around for far too long not to re-use actors from time to time, and that’s before we factor in spin-off shows such as Class and The Sarah Jane Adventures.
We already know that Peter Capaldi has been both Lobus Caecilius (in “The Fires of Pompeii”) and the Twelfth Doctor, as well as John Frobisher in Torchwood: Children of Earth, but his is by no means the only face to have reappeared in the Whoniverse more than once. 
Here’s a rundown of some of the show’s most frequent fliers!
1. Mark Gatiss
The first and least surprising addition to this list is the multi-talented Gatiss, writer of the first "New Who" story not written by Russell T Davies (“The Unquiet Dead”). As well as writing, he made his acting debut in season three, playing Professor Richard Lazarus, the youth-obsessed inventor in “The Lazarus Experiment” and the Captain (no spoilers) in "Twice Upon a Time." Then there are his uncredited appearances as a Spitfire pilot in “Victory of the Daleks” (reprised in “A Good Man Goes to War”)  and as the rubber-faced Gantok at the beginning of “The Wedding of River Song.”
And that’s without counting his numerous appearances in other Doctor Who media, from audio adventures to novelizations. The man keeps busy, is the point.  
2. Geoffrey Palmer
There are very few quality British TV shows of the 1970s and 1980s that Palmer didn’t appear in at some point, and Doctor Who is definitely no exception. He had role in one of the Third Doctor’s earliest adventures, playing Edward Masters in “The Silurians.” He then popped up two years later, taking a more authoritative role as the Administrator (he always played figures of authority well) in “The Mutants.”
But for modern Who fans he will always be best known as Captain Hardaker, another stern boss but this time the pilot of the starship Titanic, in “Voyage of the Damned.”
3. Christopher Benjamin
Fans of the Big Finish Jago and Litefoot series will be well familiar with Benjamin’s plummy tones and deft portrayal of posh authority figures. He played theater owner Henry Gordon Jago in the very highly regarded Fourth Doctor story “The Talons of Weng Chiang,” and that character went on to defend the Earth time and again in the spin-off audio series. Christopher had already appeared as Sir Keith Gold in the Third Doctor alternative reality epic “Inferno.”
When the new series came around, his previous services to Doctor Who were rewarded with the past of Colonel Hugh in the Agatha Christie romp “The Unicorn and the Wasp.” And those are only the roles he got. He had previously been up for a part in both the Second Doctor story “The Evil of the Daleks” and the Fourth Doctor adventure “Pyramids of Mars.”
4. Jean Marsh
It’s not that common for actors who have formerly played companions to return in other roles, but Marsh’s experience is slightly different from the norm. She first appeared as Richard the Lionheart’s sister Joanna in the historical epic “The Crusade,” before taking the role of Sara Kingdom in the First Doctor story epic “The Daleks' Master Plan” — a part she has played again for Big Finish audio adventures. Her third appearance was as Morgaine, the witch, pitted against the Seventh Doctor (and the Brigadier)  in “Battlefield.”
And if you look carefully at the party scenes in the Doctor Who biopic “An Adventure in Space and Time,” she makes an uncredited appearance as a background guest. Whovian for life!
5. Bella Emberg
The crossover between the worlds of Benny Hill and Doctor Who is sparsely populated, but Emberg managed the jump three times, and very nearly managed a fourth. Having made a name for herself as a comedic actress in bawdy sketch comedy shows, she took an uncredited role as a nurse in the Third Doctor’s second adventure, “The Silurians,” and then appeared again a short time later, as a kitchen maid in “The Time Warrior.”
Her most notable (and actually named) role came during the Tenth Doctor’s era, in which she played Mrs. Croot, friend of Rose and Jackie Tyler, in “Love and Monsters.” It was a part she went on to film a second cameo for, and it was due to appear in “The Runaway Bride,” but that scene was taken out in the final edit.
6. Christopher Ryan
On a similar comic note, Ryan is most famous among British TV fans for playing the part of Mike Thecoolperson in the riotous comedy The Young Ones.
He’s also a Sontaran. And as they’re a clone race, he’s appeared as more than one example of his species. He was General Staal in “The Sontaran Stratagem” / “The Poison Sky” and Commander Stark in “The Pandorica Opens,” and his face also appears in “Face the Raven.” Perhaps his weirdest appearance to date, however, was as the diminutive (and blue) Lord Kiv, whose brain was transplanted into the body of the Sixth Doctor’s companion Peri Brown in “Mindwarp.”
7. Donald Sumpter
The most recent incarnation of the fabled Time Lord Rassilon (as seen in “Hell Bent”), Donald Sumpter is a British character actor who has been playing stern rotters for decades. His first appearance in Doctor Who goes back to the sixties, as he played Enrico Casali in the Second Doctor Cyberman adventure “The Wheel in Space.” He then appeared a couple of years later as Commander Ridgeway, facing down the imminent invasion of “The Sea Devils.”
8. Robert Goodman
Robert Goodman has a peculiar claim to fame, in that he has played a lot of people in Doctor Who, but only one of them had a name and words to say, and therefore he only has one credit. If you’re familiar with the care home part of “Listen,” you’ll remember Robert as Reg, the night porter whose coffee was pinched by the Twelfth Doctor.
But that’s just the beginning. Robert also appeared as Mandrel in “Nightmare of Eden,” a citizen in “Full Circle” (both Fourth Doctor), a Gallifreyan in “Arc of Infinity,” a party guest in “Enlightenment,” a colonist in “Frontios” (Fifth Doctor), a crew-member in “Resurrection of the Daleks,” and both a loader and an officer aboard the Hyperion III in “Terror of the Vervoids.”
9. Louis Mahoney
Two fine British character actors in a row now, both of whom appeared three times, twice in the classic series and once in the modern era. Remember old Billy Shipton in the “Blink” episode? The old man in the hospital bed who’d been sent back in time by the Weeping Angels? He was played by Mahoney, who had appeared as Ponti in the Fourth Doctor adventure “Planet of Evil,” and as a Newscaster in “Frontier in Space.”
10. Tony Osoba (Photo: BBC)
And then there’s Osoba, who made a huge mark on British TV audiences as McLaren in the classic 1970s prison sitcom Porridge. He appeared as Lan in the Fourth Doctor story “Destiny of the Daleks,” Kracauer in the Seventh Doctor story “Dragonfire,” and more recently, the elderly Duke in the Twelfth Doctor story “Kill the Moon.”
11. David Troughton
You may recognize that surname, as David is the son of Patrick Troughton, who played the Second Doctor. He made two appearances in Doctor Who stories that featured his father, first as an unnamed guard in “The Enemy of the World” and second as the World War I soldier, Private Moor, in “The War Games.”
In the Third Doctor era, he made his mark as King Peladon – a character he has gone on to play in several Big Finish productions – in the multi-monster regal epic “The Curse of Peladon.” But most recently, he played the mild mannered Professor Hobbes, one of the terrified community of trapped travellers in “Midnight.”
Who is your favorite frequent Doctor Who flier?